While the duo's paths have never crossed, they both played in the prestigious Varsity Cup, and the new arrival was put in contact with Venter to provide the inside track on life at Scotstoun.
The 34-year-old was an immensely popular figure, and his departure last summer sparked a wider debate about the value of non-Scottish qualified players. Franco Smith has repeatedly stressed the importance of foreign players, especially with Glasgow's squad decimated during international breaks, and Scottish Rugby have backed him to sign Van der Merwe from the Pumas.
So just what exactly did the 27-year-old ask Venter before agreeing to his Scotstoun move? Scotland Rugby News spoke to the former Warrior to find out.
"He gave me a ring and asked me a few questions just of how the UK is compared to South Africa, including the finer details.
"It's nice to speak to someone that's been through the whole thing. I told him he must take it with both hands.
"It will be the best decision for his rugby career and in his life.
"It will be a step up, but if you look at him, like the way he plays, he's very physical and usually the step up is physical.
"If you look at his body and how strong he is and fast, I think he will adapt very easily to it. And I think just the system at Glasgow is very good, with the way Franco coaches people.
"If you have a coach like that, it's just easier to perform than at other places where there's no space, the system doesn't create space and you must pull a rabbit out of a hat. I think the way Glasgow is coached just makes it easier."
Warriors fans remain relatively in the dark over the attributes of their new signing, as not many have watched him regularly in South Africa.
As a fellow back-row, Venter is perfectly qualified to provide the lowdown on what Glasgow fans can expect from Van der Merwe.
"I think he'll be very good at Glasgow because he's big and he runs with the ball," said Venter.
"He likes the contact and he's hard-working, so I think we're gonna see a lot of ball-in-hand carries - just playing rugby and running with the ball and enjoying it.
"I think he'll go into the grind like a Matt Ferguson type of guy, like a good all-rounder. Matt is a really good player. He also likes the grind. That's the thing that I like about Matt a lot because when it gets tough... like if I go to a dogfight, I'll take Matt.
"I think it's one of those, more or less it's the same type of player, can play six, seven, eight and all this stuff. So I think he'll definitely be in that category."
Glasgow are losing a talismanic figure in their back-row this summer in Jack Dempsey, with the Scotland international heading for Japan. The 32-year-old has been an excellent servant for the Warriors, and Venter is a massive admirer of his former team-mate.
"I think Jack is a big loss for Glasgow, definitely," he said.
"He's just exceptional. If you look at the way he played this season, my oh my, yeah, it's incredible. Speed, power, skill, just ripping it up. And I must say, I also enjoyed playing with Jack because he has so much skill.
"You can throw him offload anywhere, he'll catch it. And then he'll offload it as well, you know? So it's fun to play with players like that, that have that type of skill that you can know, you can just throw it and they'll catch it and you'll go on."